Specific surface area refers to the surface area of the raw material per unit weight, unit is m2/g. The specific surface area is divided into two kinds of outer specific surface area and internal specific surface area. The ideal non porous materials have only outer surface area, but the raw materials with pores have internal specific surface areas and internal specific surface area.
Silica fume’s specific surface area: 20-28m2/g
Calculation method of specific surface area of micro silica fume:
The particle size of silica fume samples can be conveniently measured by transmission electron microscopy. The length of the scale is 100nm. It can be seen that the particle size of silica fume sample is between 10-100nm and the average particle size is 30-40nm, 40nm as for example.
1. Volume of single grain micro silica fume V=4/3×π×(40×10-9)3=2.68×10-22m3
2. Surface area of single grain micro silica fume: S=4π×(40×10-9)2=2.01×10-14m2
3. The apparent specific gravity of the silica fume is 2600 kg/m3, and the number of microsilica particles per kg is：1/2600÷2.68×10-22=1.44×1018。
So the surface area of the silica fume per kg is : 1.44×1018×2.01×10-14=29000 m2
